Battery Terminal Corrosion

[jimthesail]

Ahoy ! Have a large growth of furry corrosion on negative terminal of port battery only although isolator switch is off. Assume electrolytic action but where from and why one side only ? Tidal saltwater.
Jim

[s/v Jedi]

Originally Posted by jimthesail

Ahoy ! Have a large growth of furry corrosion on negative terminal of port battery only although isolator switch is off. Assume electrolytic action but where from and why one side only ? Tidal saltwater.
Jim

I’ve seen this happen when the seal between battery case and terminal was broken. This can happen if it has been loaded by the attached cable pulling on it.

[jimthesail]

Checked terminal and sealed OK so dismissed suggestion ! But, lo and behold, when I extracted battery to clean and charge found alternator pulley had gouged a neat hole in centre top corner. Suspect vapour forms an external battery in the atmosphere and produces the growth which is soft and furry ! Problem solved, I hope ?
Thanks
Jim

[s/v Jedi]

Originally Posted by jimthesail

Checked terminal and sealed OK so dismissed suggestion ! But, lo and behold, when I extracted battery to clean and charge found alternator pulley had gouged a neat hole in centre top corner. Suspect vapour forms an external battery in the atmosphere and produces the growth which is soft and furry ! Problem solved, I hope ?
Thanks
Jim

It means you got acid vapor over parts like the pulley, belt etc. Wash that with some baking soda and water, then rinse well. I often dry metal parts with heat gun and wd40 (which is biodegradable) then buff with clean microfiber cloth

[jimthesail]

Ah Ha ! and yesterday when tipping battery to check my repair did in fact find drops around terminal post so it did leak !
Cheers
Jim

[Michael Cobbe]

To stop rust on terninals I put Vaseline on them, it doesn't affect anything.

[billknny]

Originally Posted by jimthesail

Suspect vapour forms an external battery in the atmosphere and produces the growth which is soft and furry !

And external, gas phase, battery? QUICK Run, do not walk, to the patent office with that one!